As predicted, I'm knee-deep in oak leaves.
I remember reading once that there are twenty-some species of oaks indigenous to Maryland. With all the clarity and imperfection of memory, I can see the newspaper (an inside page) where I read this, but not the exact number (23? 28?), nor the name of the newspaper. Was it the Post? The Sun? The local crabwrapper? Was it in a story about the final collapse of the Wye Oak or one of the occasional surveys of Maryland's biggest trees?
I can't remember. The only thing that stuck is the 20+ species of native oak. It seems to me you could spend several lifetimes getting to know those oaks.
Here are four of them.
Clockwise from top left: Quercus michauxii, Q. rubra, Q. alba, Q. falcata. Or, in the vernacular: Swamp Chestnut (or Basket) Oak, Northern Red Oak, White Oak, and Southern Red Oak. I gathered these from my front walk; I suspect that if I walked down the street I might find a couple more species.